Pedal clavier switch mechanism



Jan. 20, 1953 L. HAMMOND ET AL 2,626,325

PEDAL CLAVIER SWITCH MECHANISM Filed NOV. 2, 1949 3 Sheets-Sheet l N d) l N N I WWW:

Jan. 20, 1953 HAMMOND ETAL 2,626,325

PEDAL CLAVIER SWITCH MECHANISM Filed Nov. 2, 1949 5 Sheets-Sheet 2 Jan. 20, 1953 1 HAMMOND ETAL 2,626,325

PEDAL. CLAVIER SWITCH MECHANISM Filed NOV. 2, 1949 3 Sheets-Sheet 3 il 2%. J 3% W @Kfig/J.

Patented Jan. 20, `1953 PEDAL CLAVIER SWITCH MECHANISM Laurens Hammond, Chicago, and George H. Stephens, Glencoe, Ill., assignors to Hammond Instrument Company, Chicago, Ill., a corporation of Delaware Application'November 2, 1949, Serial No. 125,106

(Cl. 20G-5) 4 Claims.

Our invention relates generally to switch 'meclranisms for electrical musical instruments and more particularly to Vpedal operated latching switch mechanisms.

In instruments of the type shown in the patent to L. Hammond and J. M. Hanert, No. 2,480,132, it is desirable to provide pedal operated switches which, when operated by a pedal, are latched in operated position until another pedal is depressed. In this way a sustained tone may be produced without requiring the player to keep his foot on the pedal. The switch mechanism forthis purpose must be reliable and quiet in operation, must be of light weight, and compact. Ity is therefore the primary object of our invention to provide a switch mechanism having these characteristics and which may be economically produced.

Other objects will appear from the following description, reference being had to the accompanying drawings in which:

Figure l is a right side elevational View of our improved pedal clavier switch mechanism, a portion of the case therefor being shown in section;

Figure 2 is a fragmentary plan view thereof;

Figure 3 is a horizontal sectional view taken on the line 3-3 of Fig. l; and

Figures 4v and 5 are vertical sectional views taken on the lines 4-4 and 5-5 of Fig. 3.

As more fully shown in our copending application,l Serial No. 11,455, led February 27, 1948, which has matured into PatentlNo. 2,508,514, a pedal clavier for an instrument of the type shown in said Patent No. 2,480,132 comprises twelve pedals arranged in a manner similar to those of an organ. In Fig. 2 there are shown but two natural pedals l and a single sharp pedal I2, which are intended to be representative of the complete pedal clavier of twelve pedals. Each of the pedals l0 is held upwardly against a fulcrum I4 by a relatively strong` coil spring IE, while each of the sharp pedals is held against its fulcrum I8 by a similar spring 20. The pedals and their supports are mounted in a supporting frame 22 which is suitably secured in the instrument case 24.

A base plate 20 and a housing 28 aresuitably secured to the frame 22 by bolts 30. As best shown in Figs. 3, 4 and 5 the switch mechanism within the housing 28 is mounted between a plurality of frame plates 32 which are held in suitably spaced relation by a notched strip 38 and by a notched strip 34 which extends through elongated slots 36. A `pair of wires 4,0; extending through the slots 36 hold the notches of the strip 34 in engagement with the vertical frame plates 32, while the strip 38 is held in place by a plurality of screws 42 threaded in an anchoring bar 44 which extends through suitable slots 46 formed in the plates 32. The frame plates are also secured to angles 50 and 5l by screws 52 which'are threaded in anchoring plates 54 and 55. The frame plates 32 are thus rigidly and firmly joined.

A tubular rock shaft 5S has small diameter pins 58 secured in its ends which extend through suitable bearings $0 mounted in bearing plates 52 (Fig. 5) secured to the end frame plates 32. The shaft 56 has a plurality of bell cranks 64 secured thereto as by welding, soldering or brazing. An arm 86 is similarly secured to the shaft 5%. The bell crank G4 and arm B are of baillike construction for the sake of rigidity, strength and lightness. The rearwardly projecting arm 58 of each of the bell cranks Bt normally rests upon the felt padded end'of a push rod l0 suitably secured to each of the pedals l0, i2. The push rods 10 extend through large openings 12v, 'I3 in the base plate 26 and in an inverted channel l, and slide through a sound deadening felt pad 'Iii which is held in place by the channel 14, the channel 'M being suitably secured to the base plate 26. The hollow shaft 56 together with all parts carried thereby is biased to swing clockwise (Fig. 4) by a tension coil spring 89 which is stretchedv between the arm t6 and the anchoring strip 55.

The upwardly extending armor each of the b ell cranks 6 has a latch operator 82 secured thereto, this operator being preferably made of a suitable sheet plastic and riveted to the arm of the bell crank 65. The operators S2 are adapted to engage leaf spring latches 84 which are secured at their lower ends to depending arms 86 of switch frames 88. The switch frames 88 are secured to the crossbar 38 by screws 90 which also clamp switch arms 92 in place, the metallic parts being separated by suitable sheets 93, 94 and 95 of insulating material. rThe switch arm 92 and the sheet 95 have rectangular openings S6 and 91 respectively through which the depending arm 86 extends. rThe forward crosspiece portion of the sheet 95 serves as a stop to limit forward lexure or its associated leaf spring latch 84. The forward crosspiece of the arm 92 has a short length of contact wire Q8 welded thereto for engagement with three complementary contact wires 99 which are Welded beneath the trfurcated end portions of flexible resilient switch arms 100. These switch arms are secured to the forward end crosspiece portion of the switch frames 88 by bolts |02, which also clamp a reinforcing leaf spring |04 in place beneath each of the switch arms |00. The outer end of each spring |04 engages a switch actuator |06 which is a strip of insulating sheet plastic and which is guided for substantially vertical movement in slots formed in the notched strip 34 and in the base plate 26. The lower end of each of the actuators |06 extends through the space between the shaft 56 and the bail portion of its associated bell crank 64, through a slot in the base plate 26, and is held in contact with one of the keys I or by the leaf spring |04. By this means the actuator |06 is held in position so that it will not vibrate or rattle. It will be understood that it is desirable to have some lost motion of the actuator |06 relative to the leaf spring contact finger or arm |00 to allow for unavoidable discrepancies in the dimensions of the various parts of the mechanism. However, such lost motion would result in noisy operation if the leaf spring |645 were not provided,

The movement of the rearward ends of the keys l0 is limited by a felt upstop l0 and a felt downstop ||2 which are suitably held in place by shouldered studs 30. Counterclockwise swinging movement of the rock shaft 56 is limited by the engagement of the arm 66 with a felt pad H4 which is secured to a fixed bracket H6.

As best shown in Fig. 5, a bushing IIB is secured to the right-hand pivot 58 of the rock shaft 56 and this bushing has a radially extending switch operator |20 fixed thereto. An angle bracket |2| is secured to the right-hand frame plate 32 by screws |22 which also serve to attach the bearing plate 62 to the frame plate. A pair of insulating supports |26, |25 are riveted to the horizontal portion of the bracket i2 i. A flexible bifurcated switch arm |26 is riveted to the support |24 while a rigid switch member |28 is riveted to the insulating support |25. The member |28 and the bifurcated ends of switch arm |26 have cross wires |30 of suitable contact alloy welded thereto respectively.

Whenever one of the pedals is depressed,its push rod l0 will eng-age the horizontal arm 68 of its associated bell crank 6d and swing the latter, and the rock shaft 56, counterclockwise to substantially the dotted line positions shown in Fig. 4. At the same time the actuator |06 will flex the leaf spring |011 upwardly until it engages the resilient switch arm lili) raising the latter from contact with the switch arm S2. At the same time operators 82 of all the bell cranks 6s will engage their associated latch springs 34, flexing them to the dotted line position shown in Fig. 4. Upon releasing the depressed pedal, the rock shaft will be rotated in clockwise direction by the spring 80 and operators 82 will swing away from the latch springs 82. The latch spring Bil associated with the key which was depressed will engage beneath the end of the resilient switch arm |00 associated therewith `and hold the latter in the position in which it is shown in full lines in Fig. 4. The latch springs St associated with the other keys will :abut against the ends of their associated switch arms |66 since the latter will not have been flexed upwardly but instead will be in contact making position. The relationship of the parts is such that the latch springs 82 will be permitted to swing into latching position before the actuator |06 has moved downwardly a sufcient distance to permit the ends of the switch arm |00 to interfere with the operation of the latch. The switch arm which is latched in the 2,626,825 l i y 4 open position, as shown in full lines in Fig. 4, will of course be released and permitted to move to contact making position immediately upon depression of another pedal.

Whenever any of the pedals is depressed the rock shaft is swung counterclockwise as shown in Fig. 5 so as to permit the switch arm |26 to fiex downwardly `and make contact with the switch member |28.

The fact that each of the switch arms |00 is trifurcated and is provided with three contact wires 99, enormously reduces the possibility that the switch might fail to make contact due to the presence of dust or dirt. Similarly the fact that the switch arm |26 is bifurcated greatly reduces the possibility of failure to make contact.

The parts of the mechanism are mechanically strong but nevertheless light in weight. They therefore have little inertia, and may be operated rapidly without producing objectionable noises.

While we have shown and described a particular embodiment of our invention, it will be Iapparent to those skilled in the art that numerous modifications and variations may be made in the form and construction thereof, without departing from the more fundamental principles of the invention. We therefore desire, by the following claims, to include within the scope of our invention all such similar and modified forms of the apparatus disclosed, by which substantially the results of the invention may be obtained by substantially the same or equivalent means.

We claim:

1. In a switch mechanism for a pedal clavier comprising a plurality of pedals, a rock shaft, a plurality of bell cranks secured to the rock shaft and each having an arm thereof forming a unidirectional driving connection between one of the pedals and the shaft, a spring to rotate the shaft in a direction opposite to that in which it may be rotated by the depression of a ped-al, a switch including a resilient arm for each pedal, an actuator and a spring forming a resilient lost-motion connection between each pedal and its associated switch arm, a resilient latch for each switch to hold it in operated condition, means on the other arm of each bell crank to release its associated latch, and means forming part of each switch for preventing operation of its associated latch.

2. A switch mechanism for the pedal clavier of an electrically controlled musical instrument comprising reciprocable switch actuators for operation by the clavier pedals respectively, a switch for each of the pedals for operation by the associated actuator, each switch comprising a long and a short rigid hollow rectangular frame, the long frame having an arm integral therewith and depending freely through the opening in the short frame, means including insulating plates for holding the frames in insulated spaced relation, a flexible switch arm secured to the long frame with parts thereof in alignment with the opening in the short frame and arranged to make contact with the short frame, and a leaf spring latch secured at its lower end te the lower end of the depending arm and having its upper end extending through the opening in the short frame and held from contact with the latter and in position beneath the end of the flexible switch arm by one of the insulating plates.

3. The combination set forth in claim 2 in which the contact making end of the flexible switch arm is divided into a plurality of contact making fingers, and in which each of the fingers has a short length of contact wire welded thereto.

4. In an electrical musical instrument having a plurality of pedals, a plurality of switches, one for each pedal and each including a resilient flexible switch arm, a resilient latch for each switch arm effective to hold the switch in operated position, means operated by the depression of any of the pedals to move all of the latches out of the paths of the switch arms and to permit all of the latches to move into the paths of movement of the switch arms during the early part of the return stroke of the pedal, a switch operator for each pedal for transmitting motion from the pedal to the switch arm, and a spring for each operator normally holding the operator a short distance away from the switch arm so as to provide some l5 6 lost motion of the operator relative to its switch arm during the initial portion of the downward stroke of its pedal.

LAURENS HAMMOND. GEORGE H. STEPHENS.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,531,138 Satterstrom Mai'. 24, 1925 2,414,343 Stoeck et al. Jan. 14, 1947 2,480,132 Hammond et al. Aug. 30, 1949 

